1. Field of the Invention
The present invention relates to a lens barrel of an optical apparatus such as a camera or the like, and more particularly to a lens barrel having a mechanism arranged to move a lens by means of an actuator.
2. Description of Related Art
It has recently become a main trend to provide cameras with an AF (automatic focusing) function of automatically carrying out focus adjustment. A camera of this type is arranged to adjust focus, for example, by driving a focusing lens system with a motor disposed within a lens barrel.
Meanwhile, in order to improve the operability of large-sized lens barrels such as a large-aperture telephoto lens during the photo-taking operation, many of them have come to be manufactured to have various functions. For example, since the depth of field of a lens such as a telephoto lens with a large aperture is shallow, an object of shooting is apt to be missed or the lens is apt to be automatically focused on a wrong object, or it is hardly possible to adequately follow a fast moving object during a panning operation. To solve this problem, such a lens is sometimes used by fixing its focus. For this purpose, a lens barrel of the lens is provided with a focus lock switch. The focus lock switch permits the focus fixing action even during an AF photo-taking operation. It is also conceivable to obviate the necessity of an AF starting operation of half pushing a release button on the camera, by arranging an AF start switch in a position near to a part of the lens barrel where the left hand of a camera user comes in holding the lens barrel, so that the release button of the camera can be arranged to be used only for operating a shutter.
Further, some of the recently marketed lenses are provided with an image stabilizing function of automatically correcting image shakes. A lens of that kind is arranged, for example, to have an image-shake correcting lens system in combination with an image stabilizing switch disposed at its lens barrel and to correct image shakes by operating the image stabilizing switch to drive the image-shake correcting lens system.
These operation switches mentioned above are arranged to be always easily operable irrespective as to whether the camera user is holding the camera in its vertical posture or in its horizontal posture and whether the camera is held by hand or held on a unipod or on a tripod. For this purpose, these operation switches are allocated, for example, at equally spaced four positions along the outer circumferential surface of an external fixed tube 101, as indicated by reference numeral 102 in FIGS. 8A and 8B.
In allocating the focus lock switches, the AF start switches or the image stabilizing switches in a plurality of equally spaced positions along the outer circumferential surface of the external fixed tube 101, the conventional lens barrel is arranged, for example, as shown in FIG. 9. Referring to FIG. 9, operation buttons 102, electric switches 104 and switch fixing members 103 are arranged in four sets in identical shapes. The four sets are respectively secured to the external fixed tube 101 with screws 106. The conventional arrangement, however, has a drawback in respect of assembly work and thus has caused an increase in cost. Incidentally, in FIG. 9, reference numeral 105 denotes a flexible printed circuit board.
The present invention is directed to the solution of the problem of the prior art described above. It is, therefore, an object of the invention to provide a lens barrel which is arranged to facilitate assembly work, even in a case where focus lock switches, AF start switches or image stabilizing switches are allocated at a plurality of equally spaced positions along the outer circumferential surface of an external fixed tube, so that the cost of the lens barrel can be prevented from being caused to increase by difficulty in carrying out assembly work.
To attain the above object, in accordance with an aspect of the invention, there is provided a lens barrel comprising a fixed lens tube of cylindrical shape and a plurality of operation parts of push type, wherein the plurality of operation parts are interconnected by a ring-shaped elastic member and are attached to the fixed lens tube.
In the lens barrel, the ring-shaped elastic member is attached to an inner circumferential surface of the fixed lens tube.
The lens barrel further includes a second lens tube of cylindrical shape which is disposed on an inner side of the ring-shaped elastic member and which has electric switches disposed thereon respectively in positions corresponding to the plurality of operation parts, and wherein each of the electric switches is operable by operating a corresponding one of the plurality of operation parts.
In the lens barrel, the electric switches are interconnected by a flexible printed circuit board.
In the lens barrel, the ring-shaped elastic member is pushed and pressed by an outer circumferential surface of the second lens tube.
Alternatively, in the lens barrel, the ringshaped elastic member is attached to an outer circumferential surface of the fixed lens tube.
In the lens barrel, the fixed lens tube has electric switches disposed thereon respectively in positions corresponding to the plurality of operation parts.
In the lens barrel, the electric switches are interconnected by a flexible printed circuit board.
Further, in the lens barrel, the ring-shaped elastic member is provided with an antislip knurled part.
The above and other objects and features of the invention will become apparent from the following detailed description of preferred embodiments thereof taken in connection with the accompanying drawings.